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Date: Thu, 16 Feb 2006 14:18:27 +1100
From: Paul Mackerras <paulus@samba.org>
To: Andrew Morton <akpm@osdl.org>
Cc: torvalds@osdl.org, linux-kernel@vger.kernel.org, johnstul@us.ibm.com
Subject: Re: [PATCH] Provide an interface for getting the current tick
 length
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Andrew Morton writes:

> Paul Mackerras <paulus@samba.org> wrote:
> 
> > Is that enough to be worth factoring out?  Note that
> > update_wall_time_one_tick() needs both time_adjust_step and
> > delta_nsec, so to share more, we would have to have a function
> > returning two values and it would start to get ugly.
> > 
> 
> update_wall_time_one_tick() gets:
> 
> 	long delta_nsec = new_function();
> 
> and your new function becomes
> 
> 	return (u64)new_function() << (SHIFT_SCALE - 10)) + time_adj;

and update_wall_time_one_tick misses out on this bit:

		/* Reduce by this step the amount of time left  */
		time_adjust -= time_adjust_step;

That's why I said that update_wall_time_one_tick needs both
time_adjust_step and delta_nsec.  If you have a nice way to return
both values, please let me know...

Paul.